Erosion preventive device



0, 1 I w. c. HOAD 2,803,113

EROSION PREVENTIVE DEVICE Filed Feb. 20, 1952 INVE NTOR United States Patent EROSION PREVENTIVE DEVICE William Christian Head, Ann Arbor, Mich.

Application February 20, B52, Serial No. 272,564

4 Claims. (Cl. 61-4) This invention is a simple and inexpensive structural unit, essentially a form of weighted tripod, which, when numerously arranged in suitable formations, may be effectively used in controlling erosion and sediment deposition by wave and current action in natural bodies of water, in reclaiming land alongshore, in providing underwater anchorage and support for light structures that have to be built over soft or irregular or uncertain bottoms, and in other beneficial operations.

Structures designed for the protection of important harbors or highways or shores against damaging effects of wave action or for the control of currents or deposition of sediments have usually taken the form of massive and rigid walls, or rock-filled wooden cribs tied together, or braced lines of sheet piling, or rock-faced dikes, or other heavy and costly structures. Such forms as these are generally appropriate and necessary where great forces have to be opposed and where the resulting benefits are very large. But there is present and growing need for less costly structures to give at least some measure of protection to less important shores and beaches and banks and to induce or control the deposition of sediments carried by water, as in the reclamation of beaches and other shore lands, in places where the conditions are less severe; and there is special need for types of structure that can be built in large part with local materials and without the use of heavy machinery or other expensive equipment.

My invention is responsive to this need. It is a structural unit consisting essentially of a tripodal frame made up of three stiff legs of wood or other suitable material fastened together at a common point or place of junction, this frame being then weighted and, when necessary, strengthened against distortion by a mass of heavy material secured about the place of junction. One cheap and convenient form of such a structural unit is illustrated in the accompanying drawing wherein:

Figure 1 is a top plan view of a pole frame;

Figure 2 is a front elevation of the pole frame;

Figures 3 and 4 are respectively similar to Figures 1 and 2 but show the completed unit having a heavy concrete mass surrounding the pole junction;

Figure 5 is a detail view of one of the identical block sections forming the concrete mass; and

Figure 6 is similar to Figure 5 but shows the separate identical sub-sections into which the block shown in Figure 5 may be further divided if desired.

As shown in the drawing, the tripodal frame is made up of three wood poles 6 fastened together in such relative positions that each such pole is at right angles to each of the other two, as shown in Figure 1 and in Figure 2. Wood poles, when used as tripod legs, should be notched at the points where they are fitted together, and such notching is indicated in the drawing-by the numerals 7, 7; but the method of fastening the poles together, whether by spiking, bolting, binding with wire, or otherwise, is not essential. The heavy mass of concrete surrounding the junction of the poles contributes both weight and rigidity to the unit. This mass of concrete is approximately spherical in shape, although this particular shape is not essential, and is made up of three precast concrete blocks interlocked about the pole junction, clasping the three poles both above and below their place of junction, and being held together in their fitted assemblage by strong wires drawn taut across their exterior surfaces between projecting ends of the poles, as indicated by the numerals 8, 8, 8. Neither this minimum pattern of wire ties indicated by the numerals 8, 8, 8 nor any other particular pattern or method of holding the blocks together, as by mortaring or grouting, constitutes a claim under this application, the only requirement being that the several blocks assembled about a pole frame shall be held in place by some effective means, of which there are many. The resulting unit structure, as shown in Figures 3 and 4, is a tripod with three wide-spreading wooden legs, which are usually although not necessarily of equal lengths, strengthened and stiffened and heavily weighted by the rigid mass of concrete blocks, and with three upward projecting arms of suitable length, as for the fastening or holding on of any additional framework or superstructure or other attachment that may be desired. If the poles are fastened together at about their mid-points the resulting unit will have the form of a jackstone, with all six projecting ends about equal in length; any three adjacent ends may then function as the legs of the tripod. The numerals 9, 9, 9, 9, 9, 9 in Figures 3 and 4 indicate this jackstone form with the three poles joined at their mid-points.

The heavy mass arranged about the junction of the three poles of the fundamental tripodal frame may conveniently be composed of concrete, which may be either deposited and formed directly in place about the pole junction or made up of an orderly assemblage of precast blocks. In the form of unit illustrated in Figures 3 and 4 the three standard concrete blocks making up the heavy mass are identical in shape and size, thus facilitating manufacture and handling. The shape of this particular form of block is illustrated in Figure 5, which shows a block of this pattern resting on its outer surface. This standard block is also identified by the numeral 10 in Figure 4. The inner surfaces of such a block are so shaped as to fit loosely against the poles, due allowance being made here for pole irregularities. The radial surfaces, which fit against adjoining blocks, are planes and are so situated that the three blocks required for one structural unit, when wedged together and fastened in place, form a compact and orderly mass and interlock in a manner to prevent lateral slipping, thus forming a rigid bracing for the pole framework. This block pattern, also, is such that a standard block, asillustrated in Figure 5, can be molded in two identical halves, if desired, for greater convenience in handling. These half-blocks are illustrated in Figure 6, and are also indicated by the numerals 11, 11 in Figure 4; and it is obvious that six of these half-blocks and two whole blocks, can then be assembled to form the complete concrete mass, instead of three whole blocks.

Referring now more particularly to Figure 5, the concrete block section A there shown is one of three identical block sections which made up the concrete mass 10 which surrounds the junction of the skeleton frame and supports the poles'at the required angles to each other. The block is formed to provide the plane surface 12 which is adapted to engage and fit with corresponding surfaces on the other blocks making up the concrete mass. The plane surface 12 is formed to provide a semi-cylindrical cavity or recess 13 which extends diametrically of the plane $1 .1"

face 12 and is adapted to receive a side of one of the cylindrical poles of the skeleton frame.

A second plane surface 1 is formed with a radially extending semi-cylindrical recess 15 likewise for receiving one of the poles of the skeleton frame. The plane surface 14 is disposed at an angle of approximately 120 to the plane surface 12 as seen more clearly in Figure 3. The plane surface 14 extends toward the viewer, as seen in Figure 5, beyond the plane surface 12 to provide a projecting part formed by the surface 17 which intersects surface 14 and surface 18 which intersects surface 12.

A third plane surface 19 is disposed at an angle of 126 to plane surface 12 and is also provided with a radially extending semi-cylindrical recess or cavity Zil. Surface 19 extends toward the viewer, as seen in Figure 5, beyond plane surface 12 to provide a second projecting part 21 like that indicated at 6. The projecting part 2.1 includes the intersecting surfaces 22 and 23.

By employing three identical block sections such as that illustrated at A in Figure 5, a complete concrete mass unit of substantially spherical form may be provided to embrace the junction of the skeleton pole frame and give it the required rigidity as well as to provide a structure having the nccesary weight to function properly.

The manner in which the block section illustrated in Figure interfits with another identical block section is as follows: surface 25 of the plane surface 12 of one block fits against surface 25 of plane surface i 3- of another block; surface 27 of plane surface 122 of one block fits against surface 28 of plane surface 19 of the other block; surface 1.7 of the one fits against surface 18 of the other; surface 18 of the one fits against surface 17 of the other; surface 26 of the one fits against surface 25 of the other; and surface 28 of one fits against surface 27 of the other.

The block shown in Figure 5 has an additional surface which intersects surface 27 along edge 3% at right angles thereto, and also intersects surface 18 in a right angle and this additional surface fits against a similar surface of another block. The block shown in Figure 5 has another surface which intersects surface 12 along edge 31. at right angles thereto and also intersects surface 14 in a right angle, this additional surface fitting against a similar surface of another block.

The surface 26 and the corresponding surface 3?, are relieved or cut away somewhat as shown in Figure 3 by the numerals 3d and this is done to facilitate removing the block section from the mold in which it is formed.

Figure 6 illustrates the sub-sections which make up a block like that shown in Figure 5. Each sub-section or half-block Ti is identical and six of these is required to form the concrete mass shown in Figures 3 and 4.

As seen in Figure 4, each of the tie wires 8, which hold the block sections A in interfitting relation about the pole frame junction, has its opposite ends connected to the opposite projecting portions of the same pole of the frame and is drawn taut across the exterior surface of the concrete mass between the legs of the other two poles. The arrangement of the wires 3 is such that only one wire extends between each pair projecting poles so that none of the wires cross. As seen in Figure 4, the wires are thus arranged so that two wires are drawn about the exterior of each block section in properly spaced relation, that is, the two wires drawn about the exterior of each block section A divide the exterior surface thereof into approximately equal thirds.

If the block sections A are made up of t subsections ill as indicated by the dotted line course only one wire would extend across the surface of each sub-section.

Weighted tripods such as are described in this application may be used to over-ride, weight down and hold in place organized masses of brush laid down in formations alongshore suitable for the protection of earth banks and shoreline structures from the damaging effects of waves and currents and ice movements. Such weighted tripods,

Al if numerously planted over such brush formations, with their feet extending through the brush mass and into the soft bottom beneath and with their upreaching arms tied across to those of adjacent units by wire ties or other means, will anchor the brush formations in place and hold them down more effectively than the usual combination of stakes driven through the brush layer for anchorage and rocks scattered on top for weight. Also the brush, being held tighter and more continuously, is less likely to be raveled away by wave action; and the entire mat of "1 and over-riding tripods, even if lifted by the ice sheet during wintertime fluctuations in water level, will settle back into approximately its former position as the ice melts, whereas unconnected rocks tend to work down through the brush layer and become useless as and stakes once lifted out of the ground are of small value as anchors.

Weighted tripods such as described in this application, when set out in orderly rows or ranks or in other suitable arrangement, may serve as an effective and inexpensive foundation and support for light superstructures, such as platforms or causeways, that have to be carried above an area of shallow water or a marsh. Such a foundation, because of its many resting points on the soft bottom, affords a wide distribution for the weight of the superstructure, it is cheap and easy to place in position at the start, and it is readily adjustable to the requirements of settlement or upheaval later. In some or all of these respects it is superior to foundation structures now in use.

Heavily we hted, short-legged tripods made up with wood poles joined together at their mid-points may be systematically tumbled over the edge of a cutbank in a river in sufiicient numbers to form a tangled mass extending over the area subject to erosion or cutting. In tripods of this form, with all six pole ends projecting to equal lengths from the central concrete mass, any three adjacent pole ends may properly function as legs, the other three standing out to catch and hold drift and other debris.

The drawing and foregoing specification constitute a description of the improved erosion preventive device in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

I claim:

1. An erosion preventive device comprising at least three substantially rigid legs crossing each other at a common junction and projecting outwardly from said junction in a predetermined diverging relation, a weighted block at said junction, said block being composed of at least three separable pre-cast concrete block sections of identical size and shape interfitted about said junction and cooperating with each other to embrace said legs at said junction, each block section having three angularly related plane surfaces which engage corresponding surfaces of the other block sections when said block sections are held together in interfitting relation about said junction, said engaging surfaces being formed With registering grooves cooperating to define open-ended pasrespectively receiving said legs, said passages extending entirely through said block and the legs in each passage projecting in opposite directions beyond said block, means for holding said block sections in interfitting relation about said junction, one of the plane surfaces of each block section being formed with a projection thereon, said projections interfitting with each other to prevent sliding of said sections relative to each other, two of said projections cooperating with the plane surface on which one of the two is formed to define a recess receiving the remaining projection.

2. The device set forth in claim 1 in which said passages ].oosely receive said legs, and said legs are made of wood.

3. The device set forth in claim 2 in which said legs diverge at rigt angles to each other and in which said plane surfaces of each section are arranged at angles of 120 to each other.

4. The device set forth in claim 3, in which each section is formed of two separate identical subsections.

Boots et a1 Sept. 18, 1894 Smith Sept. 22, 1925 6 Smith June 11, 1929 Casey Apr. 16, 1935 Paulson Nov. 11, 1941 Machamer Oct. 29, 1946 Rehfeld Mar. 16, 1948 FOREIGN PATENTS Great Britain of 1872 

